Detian – Banyue Falls or Ban Gioc Falls are 2 waterfalls on the Quy Xuan River straddling the Sino-Vietnamese border, located in in the Karst hills of Daxing County in the Chongzuo prefecture of Guangxi Province, on the Chinese side, and in the district of Trung Khanh, Cao B?ng province on the Vietnamese side, 272 km north of Hanoi.
The waterfall falls thirty meters. It is separated into three falls by rocks and trees, and the thundering effect of the water hitting the cliffs can be heard from afar.
It is currently the 4th largest waterfall along a national border after Iguazu Falls, Victoria Falls, and Niagara Falls and was one of the crossing points for China’s army during the brief Sino-Vietnamese War. Nearby there is the Tongling Gorge accessible only through a cavern from an adjoining gorge. Rediscovered only recently, it has many species of endemic plants, found only in the gorge, and used to be used as a hideout by local bandits whose treasure is occasionally still found in the cliff-side caves.
A road running along the top of the falls leads to a stone tablet that marks out the border between China and Vietnam in French and Chinese. But there were unclear definitions in the legal documents on border demarcation and the placement of markers between the French and Qing administrations.
There are controversies regarding the border demarcation at this location specified in 1999 Viet Nam-China Treaty on Land Borderline. One faction holds that the entirety of these falls belongs to Vietnam, and that the stone tablet had been moved there some time during or after the brief Sino-Vietnamese war of 1979